Atomically dispersed nickel in CeO aerogel catalysts completely suppresses methanation in the water-gas shift reaction.

Nickel-based catalysts are widely studied for water-gas shift (WGS), a key intermediate step in hydrogen production from carbon-based feedstocks. Their viability under practical conditions is limited at high temperatures when Ni aggregates and converts CO to methane, an undesirable side product. Because experimental and computational studies identify undercoordinated Ni step sites as most active toward CH formation, we eliminate Ni step sites by atomically dispersing Ni into networked, nanoparticulate CeO aerogels.

Uncovering a hidden danger: a case report of diffuse coronary spasm concealing spontaneous coronary artery dissection.

Background: Over recent years, spontaneous coronary artery dissection (SCAD) has emerged as a no longer rare cause of acute coronary syndrome (ACS). On the other hand, coronary artery spasm (CAS) is the main cause of ischemic heart disease with non-obstructive coronary lesions. Clinical manifestations of both vary from stable angina to ACS or, rarely, sudden cardiac death.

Synthesis and applications of WO nanosheets: the importance of phase, stoichiometry, and aspect ratio.

Tungsten trioxide (WO) is an abundant, versatile oxide that is widely explored for catalysis, sensing, electrochromic devices, and numerous other applications. The exploitation of WO in nanosheet form provides potential advantages in many of these fields because the 2D structures have high surface area and preferentially exposed facets. Relative to bulk WO, nanosheets expose more active sites for surface-sensitive sensing/catalytic reactions, and improve reaction kinetics in cases where ionic diffusion is a limiting factor ( electrochromic or charge storage).

The hemodynamic performance of balloon-expandable aortic bioprostheses in the elderly: a comparison between rapid deployment and transcatheter implantation.

Background: Surgical aortic valve replacement with a rapid deployment valve (RDV) is a relatively recent treatment option. The aim of this study was to compare the hemodynamic performance of balloon-expandable (BE)-RDVs and BE-transcatheter heart valves (THVs) in a high surgical risk and frail-elderly population.

Methods: BE-THVs and BE-RDVs were implanted in 138 and 47 patients, respectively, all older than 75 years and with a Canadian Study of Health and Aging category of 5 or above.

Wellens' Syndrome from COVID-19 Infection Assessed by Enhanced Transthoracic Coronary Echo Doppler: A Case Report.

Wellens' syndrome (WS) is a preinfarction state caused by a sub-occlusion of the proximal left anterior descending coronary artery (LAD). In this case report, for the first time, we describe how this syndrome can be caused by COVID-19 infection and, most importantly, that it can be assessed bedside by enhanced transthoracic coronary echo Doppler (E-Doppler TTE). This seasoned technique allows blood flow Doppler to be recorded in the coronaries and at the stenosis site but has never been tested in an acute setting.

Photoenhanced Degradation of Sarin at Cu/TiO Composite Aerogels: Roles of Bandgap Excitation and Surface Plasmon Excitation.

Multifunctional composites that couple high-capacity adsorbents with catalytic nanoparticles (NPs) offer a promising route toward the degradation of organophosphorus pollutants or chemical warfare agents (CWAs). We couple mesoporous TiO aerogels with plasmonic Cu nanoparticles (Cu/TiO) and characterize the degradation of the organophosphorus CWA sarin under both dark and illuminated conditions. Cu/TiO aerogels combine high dark degradation rates, which are facilitated by hydrolytically active sites at the Cu||TiO interface, with photoenhanced degradation courtesy of semiconducting TiO and the surface plasmon resonance (SPR) of the Cu nanoparticles.

Stabilization of reduced copper on ceria aerogels for CO oxidation.

Photodeposition of Cu nanoparticles on ceria (CeO) aerogels generates a high surface area composite material with sufficient metallic Cu to exhibit an air-stable surface plasmon resonance. We show that balancing the surface area of the aerogel support with the Cu weight loading is a critical factor in retaining stable Cu. At higher Cu weight loadings or with a lower support surface area, Cu aggregation is observed by scanning and transmission electron microscopy.

Power of Aerogel Platforms to Explore Mesoscale Transport in Catalysis.

We describe the opportunity to deploy aerogels-an ultraporous nanoarchitecture with co-continuous networks of meso/macropores and covalently bonded nanoparticulates-as a platform to address the nature of the electronic, ionic, and mass transport that underlies catalytic activity. As a test case, we fabricated Au||TiO junctions in composite guest-host aerogels in which ∼5 nm Au nanoparticles are incorporated either directly into the anatase TiO network (Au "in" TiO, Au-TiO aerogel) or deposited onto preformed TiO aerogel (Au "on" TiO, Au/TiO aerogel). The metal-meets-oxide nanoscale interphase as visualized by electron tomography feature extended three-dimensional (3D) interfaces, but Au-TiO aerogels impose a greater degree of Au contact with TiO particles than does the Au/TiO form.

Nanosecond transient absorption studies of the pH-dependent hydrated electron quenching by HSO.

The large standard reduction potential of an aqueous solvated electron (eaq-, E° = -2.9 V) makes it an attractive candidate for reductive treatment of wastewater contaminants. Using transient absorption spectroscopy, the nanosecond to microsecond dynamics of eaq- generated from 10 mM solutions of Na2SO3 at pH 4 to 11 in H2O and D2O are characterized, resulting in the determination that between pH 4 and 9 it is the HSO3-, and not H+ as previously postulated by others, that effectively quenches eaq-.

From amorphous to nanocrystalline: the effect of nanograins in an amorphous matrix on the thermal conductivity of hot-wire chemical-vapor deposited silicon films.

We have measured the thermal conductivity of amorphous and nanocrystalline silicon films with varying crystalline content from 85 K to room temperature. The films were prepared by the hot-wire chemical-vapor deposition, where the crystalline volume fraction is determined by the hydrogen (H) dilution ratio to the processing silane gas (SiH), R  =  H/SiH. We varied R from 1 to 10, where the films transform from amorphous for R  <  3 to mostly nanocrystalline for larger R.

Static and Time-Resolved Terahertz Measurements of Photoconductivity in Solution-Deposited Ruthenium Dioxide Nanofilms.

Thin-film ruthenium dioxide (RuO) is a promising alternative material as a conductive electrode in electronic applications because its rutile crystalline form is metallic and highly conductive. Herein, a solution-deposition multi-layer technique is employed to fabricate ca. 70 ± 20 nm thick films (nanoskins) and terahertz spectroscopy is used to determine their photoconductive properties.

Oxidation-stable plasmonic copper nanoparticles in photocatalytic TiO nanoarchitectures.

Ultraporous copper/titanium dioxide (Cu/TiO) aerogels supporting <5 nm diameter copper nanoparticles are active for surface plasmon resonance (SPR)-driven photocatalysis. The extended nanoscale Cu‖TiO junctions in Cu/TiO composite aerogels-which arise as a result of photodepositing copper at the surface of the nanoparticulate-bonded TiO aerogel architecture-stabilize Cu against oxidation to an extent that preserves the plasmonic behavior of the nanoparticles, even after exposure to oxidizing conditions. The metallicity of the Cu nanoparticles within the TiO aerogel is verified by aberration-corrected scanning transmission electron microscopy, electron energy-loss spectroscopy, and infrared spectroscopy using CO binding as a probe to distinguish Cu(0) from Cu(i).

Plasmonic Aerogels as a Three-Dimensional Nanoscale Platform for Solar Fuel Photocatalysis.

We use plasmonic Au-TiO aerogels as a platform in which to marry synthetically thickened particle-particle junctions in TiO aerogel networks to Au∥TiO interfaces and then investigate their cooperative influence on photocatalytic hydrogen (H) generation under both broadband (i.e., UV + visible light) and visible-only excitation.

Electroanalytical Assessment of the Effect of Ni:Fe Stoichiometry and Architectural Expression on the Bifunctional Activity of Nanoscale NiFeOx.

Electrocatalysis of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was assessed for a series of Ni-substituted ferrites (NiFeOx, where y = 0.1 to 0.9) as expressed in porous, high-surface-area forms (ambigel and aerogel nanoarchitectures).

Rewriting Electron-Transfer Kinetics at Pyrolytic Carbon Electrodes Decorated with Nanometric Ruthenium Oxide.

Platinum is state-of-the-art for fast electron transfer whereas carbon electrodes, which have semimetal electronic character, typically exhibit slow electron-transfer kinetics. But when we turn to practical electrochemical devices, we turn to carbon. To move energy devices and electro(bio)analytical measurements to a new performance curve requires improved electron-transfer rates at carbon.

Transient Optical and Terahertz Spectroscopy of Nanoscale Films of RuO.

Solution-deposited nanoscale films of RuO ("nanoskins") are effective transparent conductors once calcined to 200 °C. Upon heating the nanoskins to higher temperature the nanoskins show increased transmission at 550 nm. Electronic microscopy and X-ray diffraction show that the changes in the optical spectrum are accompanied by the formation of rutile RuO nanoparticles.

Competitive Oxygen Evolution in Acid Electrolyte Catalyzed at Technologically Relevant Electrodes Painted with Nanoscale RuO.

Using a solution-based, non-line-of sight synthesis, we electrolessly deposit ultrathin films of RuO ("nanoskins") on planar and 3D substrates and benchmark their activity and stability for oxygen-evolution reaction (OER) in acid electrolyte under device-relevant conditions. When an electrically contiguous ∼9 nm thick RuO nanoskin is expressed on commercially available, insulating SiO fiber paper, the RuO@SiO electrode exhibits high current density at low overpotential (10 mA cm @ η = 280 mV), courtesy of a catalyst amplified in 3D; however, the mass-normalized activity falls short of that achieved for films deposited on planar, metallic substrates (Ti foil). By wrapping the fibers with a <100 nm thick graphitic carbon layer prior to RuO deposition (RuO@C@SiO), we retain the high mass activity of the RuO (40-60 mA mg @ η = 330 mV) and preserve the desirable macroscale properties of the 3D scaffold: porous, lightweight, flexible, and inexpensive.

Two-dimensional gallium nitride realized via graphene encapsulation.

The spectrum of two-dimensional (2D) and layered materials 'beyond graphene' offers a remarkable platform to study new phenomena in condensed matter physics. Among these materials, layered hexagonal boron nitride (hBN), with its wide bandgap energy (∼5.0-6.

Plasmonic enhancement of visible-light water splitting with Au-TiO2 composite aerogels.

We demonstrate plasmonic enhancement of visible-light-driven splitting of water at three-dimensionally (3D) networked gold-titania (Au-TiO2) aerogels. The sol-gel-derived ultraporous composite nanoarchitecture, which contains 1 to 8.5 wt% Au nanoparticles and titania in the anatase form, retains the high surface area and mesoporosity of unmodified TiO2 aerogels and maintains stable dispersion of the ~5 nm Au guests.